Sensitization of silver halide emulsions by merocyanines from triazolo bases



United States Patent O SENSITIZATION OF SILVER HALEE EMULSIONS BY MEROCYANlNES FRM TRIAZOL BASES Leslie G. S. Brooker and Earl J. Van Lai-e, Rochester,

N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application .lune 25, 1956, Serial No. 593,615 12 Claims. (Cl. 96-102) tageously be represented by the following general formula:

wherein R represents an alkyl group, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, allyl (vinylmethyl), ethoxyethyl, benzyl (phenylmethyl), etc. (e. g., an alkyl group of the formula CmH2m+1 wherein m represents appositive 4integer of from 1 to 4), Z represents the non-metallic atoms necessary t ycomplete a heterocyclic nucleus of the benzothiazole series or the quinoline series, n represents a positive integer of from 1 to 2, and Q represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from to 6 atoms in the heterocyclic ring, such as those of the pyrazolone series (e. g., S-methyl-l-phenyl-S-pyrazolone, 1phenyl 5 pyrazolone, 1-(2-benzothiazolyl)3 methyl-S-pyrazolone, etc.), those of the isoxazolone series (e. g., 3 -phenyl-S (4H) isoxazolone, 3 -methyl- 5 (4H)isoxazolone, etc.), those of the oxindole series (e. g., lalkyl-2,3-dihydro-Z-oxoindoles, etc.), those of the 2,4,-triketohexahydropyrimidine series e. g., barbituric acid or Z-thiobarbituric acid, as well as their l-alkyl (e. g., 1-methyl, l-ethyl, l-n-propyl, l-n-heptyl, etc.), or 1,3-dialkyl (e. g., 1,3-dimethyl, 1,3-diethy1, 1,3-di-npropyl, 1,3-diisopropyl, 1,3-dicyclohexyl, 1,3di(meth oxyethyl), etc.), or 1,3-diaryl (e. g., 1,3-dipheny1, 1,3- di(p chlorophenyl), 1,3 di(p ethoxycarbonylphenyl), etc.), or 1-ary1 (e. g., l-phenyl, l-p-chlorophenyl, 1p ethoxycarbonylphenyl, etc.) or l-alkyl-S-aryl (e. g., l-ethyl-3-pheny1, l-n-heptyl-S-phenyl, etc.) derivatives, those of the rhodanine series (i. e., 2thio2,4thiazo1i dinedione series), such as rhodanine, 3alky1rhodanines (e. g., 3-ethylrhodanine, 3-allylrho-danine, etc.) or 3-arylrhodanines (e. g., 3-phenylrhodanine, etc.), etc., those of the 2(3H) -imidazo[1,2]pyridone series, those of the 5,7 dioxo-6,7dihydro-S-thiazolo[3,2-oclpyrimidine series (e. g., 5,7 dioxo-3-phenyl-6,7-dihydro-5-thiazolo[3,2-] pyrimidine, etc.), those of the 2thio2,4oxazolidinedione series (i. e., those of the 2-thio-2,4(3H,5H)-oxazoledione series) (e. g., 3-ethyl-Z-thio-2,4-oxazolidinedione, etc.), those of the thianaphthenone series (e. g., 3-(2H)thia naphthenone, etc.), those of the 2-thio-2,5thiazolidine dione series (i. e., the 2thio-2,5(3H,4H)thiazoledione series) (e. g., 3-ethyl-Z-thio-2,5thiazolidinedione, etc.), those of the 2,4-thiazolidinedione series (e. g., 21,4-thiazolidinedione, 3-ethy1 2,4 thiazolidinedione, 3-phenyl- 2,852,384 Patented sept. 16, 195s 2,4-thiazolidinedione, 3-naphthyl-Z,4-thiazolidinedione, etc.), those of the thiazoli-dinone series (e. g.,V 4-thiazolidinone, 3-ethyl 4 thiazolidinone, B-phenyl--thiazolidinone, 3-a-naphthy1-4thiazolidinone, etc.), those of Athe 4thiazolinone series (e. g., Z-ethylmercapto-4Pthiazolinone, 2-alkylphenylamino-4-thiazolinones, 3-diphenylamino-4-thiazoliiione, etc.), .those of the 2imino2,4 oxazolinone (i. e., pseudohydantoin) series, those of the 2,4-irndazolinedione (hydantoin) series (e. g., 2,4-imidazolinedione, 3-ethyl-2,t-imidazolinedione, 3pheny12,4 imidazolinedione, 3a-naphthyl2,4imidazolinedione, 1, 3-diethyl-2,l-imidazolinedione, 1-ethyl-3-phenyl-2,4imid azolinedione, l ethyl-3-a-naphthyl-Z,4-imidazolinedione, 1,3-diphenyl-Z,4-i1nidazolinedione, etc.), those of the'2- tho2,4imidazolinedione i. e., 2-thiohydantoin) series (e. g., 2,-thio-2,4,imidazo1inedione, 3ethy12thio.2,4 imidazolinedione, 3-phenyl-Z-thio-2,4-imidazolinedione, 3-a-naphthyl-Z-thio-Z,4-irnidazolinedione, 1,3-diethyl y2- thio-2,4iniidazolinedione, 1ethyl-3phenyl2 tho 2,4- imidazolinedione,` l-ethyl3-u-naphthyl-Z-thio2,4imidaz olinedione, 1,3-diphenyl 2 tho 2,4 imidazolinedione, etc. those of the 5imidazolinone series e. g., 2npropy1 mercapto-S-imidazolinone, etc.), etc. (especially a kheterocyclic nucleus containing 5 atoms inthe heterocyclic ring, 3 of said atoms being carbon atoms, 1 of said atoms being a nitrogen atom, and 1 of s ad atoms being selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom). Y

It is, therefore, an object of our invention to provide new merocyanine dyes. A further object is to provide methods for making these new dyes. `Still anotherobject is to provide new dye intermediates. A further object is to provide photographic silver halide `,emulsions sensitized with the new dyes of our invention. Other objects will become apparent from a consideration of the following description and examples.

According to our invention, We provide the dyes represented by Formula I above by condensing a compound selected from those represented by the following general wherein R and Z each have the values given above and Xprepresents an acid radical, ,such as chloride, bromide, iodide, perchlorate, benzenesulfonate, p-toluenesulfonate, methylsulfate, ethylsulfate, etc., together with a compound selected from those represented by the following general formula:

wherein n and Q each have the values given above, R1 represents a hydrogen atom ora carboxylic acyl group, Such 2S asetyl, prenions/1, ibutyryLisQbutyrvyl, benzoyl, toluoyl, etc. (e. g., a carboxylic acyl group containing from 2 to 7 carbon atoms), and Rzfrepresents an aryl group, such as phenyl, o, mand p-tolyl, etc. (e. g., a monocyclic aromatic group of the benzene series).

The condensations can advantageously/,ble carried out in the presence of a basic condensing agent, @such as the trialkylamines (e. g., t1- i,ethylamine, tripropylamine, triisopropylamine, tributylamine, triisobutylainine, triamylamine, etc.), the N,Ndialky1anilines` (e. g., N,Ndimethylaniline, N,Ndethylaniline, etc.), the N-alkylpiperidines (e. g., N-methylpiperidine, N-ethylpiperidine, etc.), etc.

wherein Z has the values given above, with an alkyl salt represented by the following general formula:

V. Y R--X wherein R and X each have the Values given above.

Temperatures varying from about the temperature of the steam bath to about 200 C. can` be employed.

The intermediates represented by Formula IV above can be prepared by condensing a compound selected from those represented by the following general formula:

wherein Z hasy the values given above, together with acetic anhydride in the presence of astrong acid, e. g., glacial acetic acid, phosphoric acid, etc. Where the condensation is slow, improved results can be obtained by first acetylating the hydrazino group of the compound of Formula VI, purifying the acetylated intermediate by crystallization, and completing the condensation by adding fresh acetic anhydride and strong acid, and heating under reflux. The carbocyclic ring of the compounds represented by Formula VI can contain simple substituents, such as chlorine, bromine, iodide, methoxyl, ethoxyl, methyl, ethyl, phenyl, etc. Intermediates represented by Formula VI above have been previously described in Brooker U. S. Patent 2,743,274, issued April 24, 1956, and Bayer et al. U. S. Patent 2,073,600, dated March 16, 1937.

Alternatively, the `intermediates represented by Formula IV above can be prepared by condensing a compound selected from those represented by Formula VI above with an alkyl orthoacetate (e. g., methyl orthoacetate, ethyl orthoacetate, eta). Heat accelerates these condensatons and the addition of small amounts of an active solvent, such as pyridine, further accelerates the condensations. The foregoing method of preparing the intermediates represented by Formula-IV above is particularly useful in those cases where it is desired to prepare intermediates having a substituent on the carbocyclic ring of the compounds represented by Formula IV.

The following examples will serve to illustrate more fully the manner whereby we practice our invention.

Example 1 .--3-ethyl-5[ (2-ethyl-1 (2H) -s-trazolo [4,3- i al quinolylidene) ethylidene] rhodanne time 2 ethyl 1 methyl s triazolo[4,3 al quinolininm iodide (1.7 g., 1 mol), 5acetanilidomethylene-S-ethylrhodanine (1.5 g., l mol.), pyridine (l5 ml.) and triethylamine (0.5 g., 1 mol.) were reuxed together for one hour. After chilling, the dye Was ltered olf and washed with ethyl alcohol. After two recrystallizations from methyl alcohol, a 16% yield of reddish crystals with a blue reex was obtained, M. P. 226-227 C. dec.

Example 2.-3-ethyl-5-i (Z-methyl-I (2H) -s-triazolo- [3,4-bl benzothz'azolyldene)ethylidene]rhodanine 1-methyl-s-triazolo[3,4-blbenzothiazole (1.9 g., 1 mol.) and methyl p-toluenesulfonate (1.9 g., 1 mol.) were heated together at i60-170 C. for 3 hours. After cooling, 5-acetanilidornethylene-3-ethylrhodanine (3 g., l mol), pyridine (l0 ml.) and triethylamine (2 g., 2 mols.) were added, and the mixture was reuxed 30 minutes. After chilling, the dye was filtered ott and washed with methyl alcohol. The crude dye was dissolved in pyridine and precipitated with methyl alcohol. A 23% yield of scarlet powder was obtained, M. P. 276-277 C. dec.

Analysis.-Calcd for C16H14N4OS3: C, 51.3; H, 3.8. Found: C, 51.4; H, 3.7.

l-methyl-s-triazolo[3,4-hlben2othiazole( 1.9 g., 1 mol.) and methyl p-toluenesulfonate (1.9 g., 1 mol.) were heated together at 15G-160 C.for three hours. After cooling, 5 acetanilidomethylene 3-ethyl2-thio-2,4oxa z'olidinedione (2.9 g., 1 mol.), pyridine (10 ml.) and triethylamine (2 g., 2 mols.) were added and the mixture reuxed for twenty minutes. The reaction mixture was diluted to 200 ml. with methyl alcohol and then chilled. The crude dye was ltered ol and washed with methyl alcohol. The dye was dissolved in pyridine and precipitated with methyl alcohol. A 54% yield of orange needles was obtained, M. P. Z50-251 C. dec. f

Example 4.--3-ethyl-5-l (Z-ethyl-l (2H -s-triazolo [3,4- bl benzothazolyldene) ethylidenel rhodanine 1-methyl-s-triazolo[3,4-blbenzothiazole (1.9 g., 1 mol.) and diethyl Vsulfate (1.6 g., l mol.) were heated together at 15G-160 C. for tour hours. After cooling, S-acetanilidomethylene--ethylrhodanne (3 g., 1 11101.), pyridine ml.) and triethylamine (2 g., 2 mols.) were added and the mixture reuxed for twenty minutes. 'I'he reaction mixture was diluted to 200 ml. with methyl alcohol and then chilled. VThe crude dye was filtered oil and washed with methyl alcohol. The dye was dissolved in pyridine and precipitated with methyl alcohol. A 45% yield of ne, reddish-brown needles was obtained, M. P. 244-245 C. dec.

1methylstriazolo[3,4-blbenzothiazole (1.9 g., 1 mol.) and diethyl sulfate (1.6 g., 1 mol.) were heated together at ISU-160 C. for four hours. After cooling, S-acetanilidomethylene-3-ethyl-1-phenyl-2-thiohydantoin (3.6 g., l mol.), pyridine (10 ml.) and triethylamine (2 g., 2 mols.) were added and the mixture reiluxed for thirty minutes. After cooling, the reaction mixture was treated with ether, the ether layer decanted off, and the residual oil washed again with ether. A small amount of ethyl alcohol was added and the oil became crystalline. The mixture was ,chilled and the solid filtered od and washed with ethyl alcohol. After two recrystallizations from methylalcohol, thedye was obtained as brownish crystals iria 36% yield, M. P. 16S-166 C. dec.

1methylstriazolo[3,4-blbenzothiazole (1.9 g., 1 mol.) and diethyl sulfate (1.6 g., 1 mol.) were heated together at G-160 C. for four hours. After cooling, 5- acetanilidomethylene 1,3 diethyl-Z-thiobarbituric acid (3.45 g., l mol), pyridine (10 ml.) and triethylamine (2 g., 2 mols.) were added and the mixturerre uxedfor thirty minutes. The reaction mixture was diluted to 200 ml. with methyl alcohol and then chilled. The crude dye was ltered ofr and washed `with methyl alcohol. The dye was dissolved in pyridine and precipitated with methyl alcohol. A 40% yield of yellow needles was obtained M. P. 256-260" C. with previous shrinking.

lmcthylstriazolo[3,4-blbenzothiazole (1.9 g., l mol.) and d iethylsulfate (1.6 g.,'1 mol.) were heated together at -160."Y C. for four hours.v After cooling, 4-anilinomethylene-3-methyl-l-p-sulfophenyl-S-pyrazolone (3.6 g., l mol.), pyridine (l0 ml.) and ytriethylamine (2 g., 2 mols.) were added and the mixture reiluxed for one and one-half hours. After cooling, the reaction mixture was treated with ether, the ether layer decanted oli, and the residual oil washed again with ether. The oil remaining was dissolved in a small amount of ethyl alcohol and the solution made acid with conc. hydrochloric acid. After cooling, the crude dye was Iiltered o and washed with methyl alcohol. The dye was dissolved in methyl alcohol with the addition of triethylamine, the solution was iiltered and the solution made acid with hydrochloric acid. The dyewhich separated. was ltered ol and washed with methyl alcohol. After repeating the abovepuriiication, the dye was obtained as brownish crystals in a 22% yield, M. P. 289-290 C. dec.

6 ethoxy l methyl s triazolo[3,4blbenzothia zole (1.17 g., l mol.) and diethyl sulfate (0.77 g., 1 mol.) were heated together at l50-160 C. for four hours. After cooling, 5 acetanilido-methylene 3 ethylrhodanine (1.53 g., 1 mol.), pyridine (l0 ml.) and triethylamine (1 g., 2 mols.) were added and the mixture reuxed thirty minutes. The reaction mixture was diluted to 100 ml. with methyl alcohol and then chilled.' The crude dye was iilter'ed off and washed with methyl alcohol. The dye was dissolved in pyridine, the pyridine solution was filtered, and the dye precipitated with methylalcohol. A 37% yield of ne orange needles was obtained, M. P. 240-241 C. dec.

l C gHs 7-chloro-1 methyl-s-triazolo[3,4-blbenzothiazole (0.9 g., 1 mol.) and diethylsulfate (0.62 g., 1 mol.) were heated together at ISO- C. for four hours. After cooling, 5 acetanilidomethylene 3 ethylrhodanine` (1.3 g., 1 mol), pyridine (5 ml.) and triethylamine (0.8 g., 2 mols.) were added and the mixture reuxed for thirty minutes. The reaction mixture was diluted to 100 ml. with methyl alcohol and then chilled. The crude dye was ltered off and washed with methyl alcohol. The dye was dissolved in pyridine, the pyridine solution was ltered, and the dye precipitated with methyl alcohol. An 18% yield of reddish brown needles was obtained, M. P. 242-243 C. dec.

l CzHn 1 methyl s uiazolo[3,4b]benzothiazole (1.9 g., 1 mol.) and diethylsulfate (1.6 g., 1 mol.) were heated together at 150-160 C. for four hours. After cooling, 5- acetanilidoallylidene 3 ethylrhodanine (3.3 g., l mol.), pyridine (20 m1.) and triethylamine (2 g., 2 mols.) were added and the mixture reuxed twenty minutes. The reaction mixture was diluted to 100 ml. with methyl alcohol and then chilled. The crude dye was ltered olf and washed well with methyl alcohol. The dye wasextracted twice with 5() ml. cold acetone. The residual dye was dissolved in pyridine, the pyridine solution ltered, and the dye precipitated with methyl alcohol. A 39% yield of green crystals was obtained, M. P. 21S-219 C. dec.

Example I] .--eihoxy-l -methyl-s-trazolo {3,4-12] Y benzothiazole A 6ethoxy-Z-hydrazinobenzothiazole (11 g., 1 mol.), pyridine (15 ml.) and ethyl orthoacetate (17 g., 2 mols.) were heated together and the temperature was gradually raised until the ethyl alcohol, formed in the reaction, distilled over. After all of the alcohol had distilled over, the temperature was gradually raised until most of the pyridine distilled over. The residue was diluted to 150 m1. with ligroin (B. P. 60-90 C.) and the mixturerchilled. The solid was ltered oi and Washed with ligroin. A 24% yield of tan crystals was obtained, M. P. l66-169 C.

Starting with 5-chloro-2-hydrazino benzothiazole and following the same procedure, an 11% yield of 7-chloro- 1 methyl s triazolo[3,4-blbenzothiazole was obtained, M. P. 3l0 C.

Example 12 .-1 -methyl-s-triazolo [4,3-:11 quinoline ethyl acetate. A 65% crude yield of colorless crystals was obtained, M. P. 15S-158V C.

Example 13.-#2-ethyl-1-methyl-s-triaxolo [4,3-111 quinolinium iodide Example 1 4 .-1 -merhyl-s-triazolo 13 ,4 -bl benzothiazole 2-acetylhydrazinobenzothiazole (10.4 g., 1 mol.), acetic anhydride (50 m1.) and phosphoric acid (0.5 ml.) were reuxed together for l hour. The reaction mixture was poured into 400 ml. of water with stirring. The mixture was made alkaline with sodium carbonate solution, and the product ltered olf and washed with water. After recrystallization from methyl alcohol an 81% yield of colorless crystals was obtained, M. P. 142144 C.

Example I5.-2-acetylhydmznobenzothazole s e \o-NH-Nnooorn \N/ Z-hydrazinobenzothiazole (33 g., l mol.), acetic anhydride (40.8 g., 2 mols.) and acetic acid (100 m1.) were refluxed together for 1 hour. The acetic acid and acetic anhydride were removed on a steam bath under reduced pressure. The residue was dissolved in ethyl alcohol (20() ml.) and the solution made alkaline with 10% potassium carbonate solution. The mixture was cooled and the solid filtered ofi, washed with water and then with ethyl alcohol. After recrystallization from methyl alcohol, a 53% yield of colorless crystals was obtained, M. P. Z13-215 C.

Analyss.-Calcd for C9H9N3OS: C, 52.1; H, 4.3. Found: C, 52.3; H, 4.3.

As noted above We have found that our new dyes spectrally sensitize photographic silver halide emulsions when incorporated therein. VThe dyes are especially useful for extending the spectral sensitivity of the customarily employed gelatinosilver-chloride, gelatinosilver-chlorobromide, gelatine-silver bromide and gelatino-silver-bromiodide developing-out emulsions. To prepare emulsions sensitized with one or more of our new dyes, it is only necessary to disperse the dye or dyes in the emulsions. The methods of incorporating dyes in emulsions are simple and are known to those skilled in the art. 1n practice, it is convenient to add the dyes to the emulsions in the form of a solution in an appropriate solvent. Methanol or acetone has proved satisfactory as a solvent for most of 01.171 new dyes. Where the dyes are quite insoluble in methyl alcohol, a mixture of methyl alcohol and pyridine is advantageously employed as a solvent. The dyes are advantageously incorporated in the finished, washed emulsions and should be uniformly distributed throughout the emulsions. The particular solvent used will, of course, depend on the solubility properties of the particular dye.

The concentration of the dyes in the emulsions can vary widely, e. g., from to 100 mg. per liter of owable emulsion. The concentration of the Ydyes will vary according to the type of emulsion and according to the elect desired. The suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art, upon making the ordinary tests and observations customarily used in the art of emulsion making. To prepare a gelatino-silver-halide emulsion sensitized with one or more of our new dyes, the following procedure is satisfactory.

A quantity of dye is dissolved in methyl alcohol or acetone (or a mixture of methyl alcohol and pyridine) and a volume of this solution, which may be diluted with water, containing from 5 to 100 mg. of dye, is slowly added to about 1000 cc. of gelatino-silver-halide emulsion, with stirring. Stirring is continued until the dye is thoroughly dispersed in the emulsion.

With most of our dyes, from to 20 mg. of .dye per liter of gelatino-silver-bromide or bromoiodide emulsion (containing about 40 g. of silver halide) suices to produce the maximum sensitizing eiect. With the finer grain emulsions, somewhat larger concentration of dye may be needed to produce the maximum sensitizing effect.

The above statements are only illustrative, as it will be apparent that the dyes can be incorporated in photographic emulsions by any of the other methods customarily employed in the art, e. g., by bathing a plate or film upon which an emulsion is coated in a solution of the dye in an appropriate solvent. However, bathing methods are ordinarily not to be preferred. Emulsions sensitized with the dyes can be coated on suitable supports, such as glass, cellulose derivativek lm, resin lm or paper in the usual manner.

Photographic silver halide emulsions, such as those listed above, containing the sensitizing dyes of our invention can also contain such addenda as chemical sensitizers (e. g., sulfur sensitizers, such as allyl thiocarbamide, thiourea, allylisothiocyanate, cystine, etc.), various gold compounds (such as potassium chloroaurate, auric trichloride, etc.) (see U. S. Patents 2,540,085; 2,597,856; and 2,597,915, for example), various palladium compounds (such as palladium chloride (U. S. 2,540,086), potassium chloropalladate (U. S. 2,598,079), etc., or mixtures of such sensitizers), antifoggants (e. g., benzotriazole, nitrobenzimidazole, S-nitroindazole, etc. (see' Mees: The Theory of the Photographic Process, Macmillan Pub., 1942, p. 460), or mixtures thereof), hardeners (e. g., formaldehyde (U. S. 1,763,533), chrome alum (U. S. 1,763,533), glyoxal (Germany 538,713), dibromacrolein (Great Britain 406,750), etc.), color couplers (e. g., such as those described in U. S. Patent 2,423,730, Spence and Carroll U. S. Patent 2,640,776, issued June 2, 1953, etc.), or mixtures of such addenda. Dispersing agents for color couplers, such as substantially water-insoluble, high boilingV crystalloidal materials, such as those set forth in U. S. Patents 2,322,027 and 2,304,940, can also be employed in the above-described emulsions.

In the manner described above, a number of the dyes of our invention represented by Formula I above were separately incorporated in an ordinary gelatine-silverchlorobromide emulsion, the dyes being added in the form of a solution in an organic solvent. The dyes were then thoroughly incorporated in the emulsions by stirring. After a short digestion, the emulsions were coated onto ordinary cellulose acetate lm supports and the coatings exposed in a spectrograph and sensitometer and then developed in the usual way. The sensitizingrange and maximum absorption for several-ofthe-` dyesiare indicated in the following table.

Dye of Example Range Max. in

3 to 560 53o 4 to 62o 56o 5 L17o-570 535 6 to 510 480 s to 615 565 9 te 615 565 10 to 68o 510,610

The accompanying drawing further illustrates our 1nvention. Each figure is a diagrammatic reproduction of a wedge spectrogram showing the sensitivityof an ordinary gelatino-silver-bromiodide emulsion containing one of the sensitizing dyes represented.` by Formula I" above. In Fig. 1, the curve depicts the sensitivity of an ordinary gelatino-silver-bromiodide emulsion sensitized with 3-ethyl-5- l 2-ethyl-1 (2H) s-triazolo l 3,4-b l benzothiazolylidene)ethylidenelrhodanine. I11`Fig. 2,-the curve depicts the sensitivity of an ordinary gelatino-silver-bromiodide emulsion sensitized with 3-ethyl-5-[(2-methyl1(2H)-striazole[3,4 blbenzothiazolylidene)ethylidenel-Z-thio-Z, 4,-oxazolidinedione. InFig 3the curve depicts the sensitivity of an ordinary gelatino-silver-bromiodide emulsion sensitized with 5[(7-chloro-2-ethyl-1(2H)striazolo 3,4-b] benzothiazolylidene) ethylidene] 3,ethy1rhoda nine. f

This application is a continuation-in-part of Aour copending application Serial No. 451,062, filed August' 19, 1954, now United- States Patent 2,786,054, issued March 19, 1957.

What we claim as our invention and desiresecured by Letters Patent of the United States is:

1. A photographic silver halide emulsion sensitized with a merocyanine dye selected from those represented by the following general formula:

2. A photographic silver halide emulsion sensitized Ywith a merocyanine dye selected from those represented by the following general formula:

l y R wherein R represents a lower alkyl group, represents a positive integer of from 1 to 2, Z represents the nonmetallic atoms necessary to complete la heterocyclic nucleus -of the benzothiazole series and Q represents the non-metallic atoms necessary-to complete a heterocyclic nucleus of the rhodanine series.

3. A photographic silver halide emulsion sensitized with Ya merocyanine dye selected from those represented by the following general formula:

Il N\ wherein R represents a lower alkyl group, n represents a positive integer of from 1 to 2, Z represents the nonmetallic atoms necessary to `complete a heterocyclic nucleus of the benzothiazole series and Q represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the 2-thio2,4oxazolidinedione series. 4. A photographic silver halide emulsion sensitized with a merocyanine dye selected from those represented by the following general formula:

wherein R represents a lower alkyl group, n represents a positive integer of from 1 to 2, Z represents the nonmetallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series and Q represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the 2-thio-2,4imidazolinedioneseries.

5. A photographic silver halideemulsion sensitized with a merocyanine dye selected from those represented by the following general formula:

wherein R represents an alkyl group, n represents a positive integer of from 1 to 2, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benezothiazole series and those of the quinoline series, and Q represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring.

7. A-photographic gelatino-silver-halide emulsion sensitized with a merocyanine dye selected from those represented by the following general formula:

12 wherein R represents a lower alkyl group, n represents a positive integer of from 1 to 2, Z represents theY nonmetallic atoms necessary to complete a heterocyolic nucleus selected from the group consisting of those of the benzothiazole series and those of the quinoline series, and Q represents the non-metallicv atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the pyrazolone series, those of the isoxazolon'e series, those of the oxindole series, those of the 2,4,-triketohexahydropyrimidine series, those of the rhodanine series, those of the 2(3H)imidazo[l,2al pyridone series, those of the 5,7dioXo-6,7dihydro5thia zolo[3,2lpyrimidine series, those of the 2-thio-2,4- oxazolidinedione series, those of the thianaphthenone series, those of the 2-thio-2,5thiazolidinedione series, those of the 2,4-thiazolidinedione series, those of the thiazolidinone series, those of the 4-thiazolinone series, those of the 2imino2,4oxazolinone series, .those of the 2,4-imidazolinedione series, those of the 2-thio-2,4imida zolinedione series, and those of the S-imidazolinone series.

8. A photographic silver halide emulsion sensitized with the merocyanine dye represented by the following formula: v

9. A photographic silver halide emulsion sensitized with the merocyanine dye represented by the ,following formula:

with the merocyanine dye represented by the following formula:

formula:

i 12. A photographic silverhalide emulsion sensitized formula:

References Cited in the l'e of this patent UNITED STATES PATENTS Brooker Apr. 27, 1937 Chemical Abstracts, 16, 3101 (abstract of Brit. Med.

Sprague Apr. 121955 OTHER REFERENCES Journal, 1922, I, S14-5).

Chemical Abstracts, 19, 530 (abstract of Proc. Roy.

10 Soc., London, 96B, 317-33, 1924). 

7. A PHOTOGRAPHIC GELATINO-SILVER-HALIDE EMULSION SENSITIZED WITH A MEROCYANINE DYE SELECTED FROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 